Robust control method for aero-engine starting control plan

Abstract

A robust control method for an aero-engine starting control plan comprises the steps that in the engine starting process of an aero-engine, according to a control program of a first redundancy fuel control plan, an acceleration fuel flow target # imgabs0 # is obtained at the current moment j, and an acceleration fuel flow fusion target # imgabs1 # at the previous moment j-1 is obtained; a fusion coefficient # imgabs2 # at the current moment is obtained through weighted calculation, and then a weight # imgabs5 # is obtained through calculation according to the fuel oil deviation # imgabs3 # of the fuel oil control plan and the acceleration deviation # imgabs4 # of the second conversion acceleration control plan; inputting # imgabs6 # into Proportional-integra control to output accelerated fuel flow at the current moment j, fusing the accelerated fuel flow with # imgabs7 #, obtaining a steady-state fuel flow target # imgabs8 # at the current moment j according to a control program of a third steady-state fuel control plan, and taking a minimum value of the accelerated fuel flow target # imgabs8 # and the steady-state fuel flow target # imgabs9 # to obtain a final fuel flow target # imgabs9 # of the starting control plan.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft engine control, and in particular to a robust control method for an aircraft engine starting control plan. Background Art

[0002] Surge is an abnormal working state that must be avoided for the normal operation of aircraft engines. However, in order to complete the start-up quickly during the starting process, it is often necessary to approach the surge boundary of the compressor. This contradiction makes the design of the starting control plan particularly strict. In order to prevent the starting surge caused by the influence of control interference factors such as starting load and starter power decay, the designed starting control plan often reserves a certain surge margin between the surge boundary to ensure the safety of the starting process. In order to further improve the transient performance of advanced engines, reducing the designed surge margin has become a feasible key means, which makes it necessary to strengthen the robustness of the starting control plan to control interference factors such as sensors, actuators and power extraction. A single starting control plan is difficult to avoid starting surge caused by a single or combined interference factor. The mixed use of multiple plans has become the main countermeasure to improve the robustness of starting control.

[0003] The currently used robust control methods for various starting control plans are either too simple, with disadvantages such as weak robustness or poor performance retention, or can only tolerate single or a few control disturbance factors and cannot adapt to the more complex control disturbance conditions in the actual engine starting process.

[0004] Therefore, in order to solve the problems of simplicity and versatility of robust control methods for various starting control plans, a robust control method for aircraft engine starting control plans with strong application capabilities is needed. Summary of the invention

[0005] To solve the above problems, the purpose of the present invention is to provide a robust control method for an aircraft engine starting control plan, which can be adapted to starting control plans of different engines and multiple control interference factors, avoid starting surge caused by a single interference factor or a combination of interference factors, and maintain a certain acceleration performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions.

[0007] A robust control method for an aircraft engine starting control plan comprises the following steps:

[0008] S100: During the engine start process of the aircraft engine, according to the acceleration fuel flow target (W f,cmd ) j , and the accelerated fuel flow fusion output (W f,acc ) j-1, get the fuel deviation ; and process the fuel deviation to obtain the normalized fuel deviation ;

[0009] S200: Based on normalized fuel deviation The penalty coefficient is calculated with the asymmetric Gaussian distribution function , according to the high pressure shaft conversion speed at the current time j The switching coefficient is calculated with the flexible switching function , and according to and Calculate the fusion coefficient ;

[0010] S300: Calculate the acceleration target value of the high-pressure shaft according to the current time j , and the actual engine high pressure shaft conversion acceleration target value obtained at the previous moment j-1 , get the converted acceleration deviation , according to the acceleration deviation , fuel deviation and fusion coefficient Calculate the weighted sum of the deviation of the converted rotor acceleration and the fuel flow deviation , output the acceleration fuel flow fusion output (W f,acc ) j ;

[0011] S400: Based on the steady-state fuel flow target (W f,steady ) j , and the acceleration fuel flow fusion output at the current time j (W f,acc ) j , and obtain the final fuel flow target (W f,final ) j .

[0012] Optionally, the normalized formula of the fuel flow deviation of the redundant fuel control plan in step S100 is:

[0013] .

[0014] Optionally, in step S100, the acceleration fuel flow target (W f,cmd ) j The calculation formula is:

[0015] ,

[0016] in, , , and Calculate the fuel control plan corresponding to different pressure sensors at the current time j.

[0017] Optionally, in step S200, the penalty coefficient , switching coefficient and fusion coefficient The calculation formula is:

[0018]

[0019]

[0020] ;

[0021] in, and is an asymmetric Gaussian distribution function with different scaling factors on the positive and negative sides, both greater than 0 and No more than 0.1, ; and are the scaling and translation coefficients of the switching function, Greater than 0 and No more than 1.

[0022] Optionally, in step S300, the deviation weighted sum The calculation formula is:

[0023] ,

[0024] in, Adjustment The scaling factor of the size, Adjustment Scaling factor for size, both greater than 0 and not more than 10.

[0025] Optionally, the final fuel flow target (W f,final ) j The calculation formula is: .

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention has few parameters for optimization and setting, is easy to use and easy to implement by algorithm, and except for a very small number of parameters that require prior knowledge to determine the initial value, the settings of other parameters are independent of the specific engine characteristics. It can be generally applied to the weighted fusion needs of two acceleration control plans, without paying attention to the disturbance characteristics of the specific plan. It has the robust control capability of single fault tolerance or combined fault tolerance for at least six control interference factors such as fuel metering error, starter power decay, compressor rear pressure sensor error, starting load increase, high-pressure compressor efficiency decay and high-pressure turbine efficiency decay. The starting process controlled by the disclosed method can avoid surge while still maintaining a certain acceleration performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a control schematic diagram of a robust control method in an aircraft engine starting controller provided by an embodiment of the present disclosure;

[0029] Figure 2 is a flowchart of a robust control method for two starting control plans provided by an embodiment of the present disclosure;

[0030] Figure 3 is an asymmetric Gaussian distribution function image provided by an embodiment of the present disclosure;

[0031] Figure 4 is a flexible switching function image provided by an embodiment of the present disclosure;

[0032] Figure 5 It is a line chart showing the statistics of the start-up time of different control methods during the start-up process under the influence of the combined interference factors of the sea level standard atmosphere provided by an embodiment of the present disclosure;

[0033] Figure 6 It is a line chart showing the statistics of minimum surge margins of different control methods during the starting process under the influence of combined interference factors of the sea level standard atmosphere provided by an embodiment of the present disclosure;

[0034] Figure 7 It is a line chart showing the statistics of the minimum surge margin after the starter is disengaged during the starting process under the influence of the combined interference factors of the sea level standard atmosphere provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] The following will refer to the attached Figures 1 to 7 Specific embodiments of the present invention are described in detail. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0036] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0037] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0038] In one embodiment, the present invention provides a robust control method for an aircraft engine start control plan, comprising the following steps:

[0039] S100: During the engine start process of the aircraft engine, according to the acceleration fuel flow target (W f,cmd ) j , and the accelerated fuel flow fusion output (W f,acc ) j-1 , get the fuel deviation ; and process the fuel deviation to obtain the normalized fuel deviation ;

[0040] S200: Based on normalized fuel deviation The penalty coefficient is calculated with the asymmetric Gaussian distribution function , according to the high pressure shaft conversion speed at the current time j The switching coefficient is calculated with the flexible switching function , and according to and Calculate the fusion coefficient ;

[0041] S300: Calculate the acceleration target value of the high-pressure shaft according to the current time j , and the actual engine high pressure shaft conversion acceleration target value obtained at the previous moment j-1 , get the converted acceleration deviation , according to the acceleration deviation , fuel deviation and fusion coefficient Calculate the weighted sum of the deviation of the converted rotor acceleration and the fuel flow deviation , output the acceleration fuel flow fusion output (W f,acc ) j ;

[0042] S400: Based on the steady-state fuel flow target (W f,steady ) j , and the acceleration fuel flow fusion output at the current time j (W f,acc ) j , and obtain the final fuel flow target (W f,final ) j .

[0043] Optionally, the normalized formula of the fuel flow deviation of the redundant fuel control plan in step S100 is:

[0044] .

[0045] Optionally, in step S100, the acceleration fuel flow target (W f,cmd ) j The calculation formula is:

[0046] ,

[0047] in, , , and Calculate the fuel control plan corresponding to different pressure sensors at the current time j.

[0048] Optionally, in step S200, the penalty coefficient , switching coefficient and fusion coefficient The calculation formula is:

[0049]

[0050]

[0051] ;

[0052] in, and is an asymmetric Gaussian distribution function with different scaling factors on the positive and negative sides, both greater than 0 and No more than 0.1, ; and are the scaling and translation coefficients of the switching function, Greater than 0 and No more than 1.

[0053] Optionally, in step S300, the deviation weighted sum The calculation formula is:

[0054] ,

[0055] in, Adjustment The scaling factor of the size, Adjustment Scaling factor for size, both greater than 0 and not more than 10.

[0056] Optionally, the final fuel flow target (W f,final ) j The calculation formula is: .

[0057] In one embodiment, if Figure 2 As shown, the present invention provides a robust control method for an aircraft engine starting control plan, comprising the following steps:

[0058] S100: During the engine start process of the aircraft engine, the acceleration fuel flow target (W) obtained at the current time j according to the control program of the first redundant fuel control plan f,cmd ) j , which is achieved by replacing the original single conversion fuel flow control plan with the P2 conversion fuel flow control plan, P 25 Calculate fuel flow control plan and P 31 The three different fuel control plans are converted into fuel flow control plans, thereby obtaining three converted fuel flow results W f,p2 , W f,p25 and W f,p31 , and take the middle value of these three results to get (W f,cmd ) j Then, according to the acceleration fuel flow obtained at the previous moment j-1, the output (W f,acc ) j-1 , subtract the front and back to get the fuel deviation , ; and divide the fuel deviation by the acceleration fuel flow target (W f,cmd ) j Get the normalized fuel deviation , ;

[0059] S200: Based on normalized fuel deviation With an asymmetric Gaussian distribution function Calculate the penalty coefficient , according to the high pressure shaft conversion speed at the current time j With flexible switching function Calculate the switching coefficient , and according to and Calculate the fusion coefficient ;

[0060]

[0061]

[0062] in and is an asymmetric Gaussian distribution function with different scaling factors on the positive and negative sides, both greater than 0 and No more than 0.1, ; and are the scaling and translation coefficients of the switching function, Greater than 0 and No more than 1.

[0063] S300: The high-pressure shaft converted acceleration target value obtained at the current time j according to the control program of the second type of converted acceleration control plan commonly used in engineering , and the actual engine high pressure shaft conversion acceleration target value at the previous moment j-1 , subtract the front and back to get the converted acceleration deviation , ,according to , and Calculate the weighted sum of the deviation of the converted rotor acceleration and the fuel flow deviation , and Input to the proportional-integral control to output the acceleration fuel flow fusion output (W f,acc ) j ;

[0064] S400: The steady-state fuel flow target (W) obtained at the current time j according to the control program of the third steady-state fuel control plan commonly used in engineering f,steady ) j , and the acceleration fuel flow fusion output at the current time j (W f,acc ) j The minimum value of the two is used to obtain the final fuel flow target (W f,final ) j , .

[0065] Reference Figure 1 , which is a control schematic diagram of a robust control method in an aircraft engine starting controller. First, based on the measurable parameters P2 and P 25 and P 31 , and use the control program of the redundant fuel control plan to obtain the acceleration fuel flow target (W f,cmd ) j , which is achieved by replacing the original single conversion fuel flow control plan with the P2 conversion fuel flow control plan, P 25 Calculate fuel flow control plan and P 31 The three different fuel control plans are converted into fuel flow control plans, thereby obtaining three converted fuel flow results W f,p2 , W f,p25 and W f,p31 , and take the middle value of these three results to get (W f,cmd ) j Then, according to the acceleration fuel flow obtained at the previous moment j-1, the output (W f,acc ) j-1 , subtract the front and back to get the fuel deviation ; and divide the fuel deviation by the acceleration fuel flow target (W f,cmd ) j Get the normalized fuel deviation ; Then, according to the normalized fuel deviation The penalty coefficient is calculated using the asymmetric Gaussian distribution function mentioned above. , according to the sensor measuring the high-pressure shaft conversion speed at the current time j The switching coefficient is calculated by the flexible switching function mentioned above , and according to and Calculate the fusion coefficient Then, according to the control program of the second engineering commonly used conversion acceleration control plan, the high-pressure shaft conversion acceleration target value obtained at the current time j , and the actual engine high pressure shaft conversion acceleration target value at the previous moment j-1 , subtract the front and back to get the converted acceleration deviation ,according to , and Calculate the weighted sum of the deviation of the converted rotor acceleration and the fuel flow deviation , and Input to the proportional-integral control to output the acceleration fuel flow fusion output (W f,acc ) jFinally, the steady-state fuel flow target (W) obtained at the current time j according to the control program of the third steady-state fuel control plan commonly used in engineering f,steady ) j , and the acceleration fuel flow fusion output at the current time j (W f,acc ) j The minimum value of the two is used to obtain the final fuel flow target (W f,final ) j .

[0066] In the above embodiment, the number of the redundancy conversion fuel control plans used can be any number greater than or equal to two, so as to enhance the ability of the start control to cope with the noise or even failure of a single sensor. The start process controlled by the method described in the present disclosure can avoid a significant decrease in surge margin caused by a single control interference factor or a combination of control interference factors, avoid the risk of surge, and can also avoid a significant decrease in acceleration performance.

[0067] In another embodiment, the normalization method of the fuel flow deviation of the redundant fuel control plan in step S100 is:

[0068]

[0069] Acceleration fuel flow target (W f,cmd ) j The calculation method is:

[0070]

[0071] in , , and Calculate the fuel control plan corresponding to different pressure sensors at the current time j.

[0072] In another embodiment, the image of the asymmetric Gaussian distribution in step S200 is as follows: Figure 3 As shown, the flexible switching function graph is as follows Figure 4 As shown, the penalty coefficient , switching coefficient and fusion coefficient The calculation method is:

[0073]

[0074]

[0075]

[0076] in and is an asymmetric Gaussian distribution function with different scaling factors on the positive and negative sides, both greater than 0 and No more than 0.1, ; and are the scaling and translation coefficients of the switching function, Greater than 0 and No more than 1.

[0077] In another embodiment, the weighted sum of the deviations in step S300 is The calculation method is:

[0078]

[0079] in, Adjustment The scaling factor of the size, Adjustment Scaling factor for size, both greater than 0 and not more than 10.

[0080] In another embodiment, the final fuel flow target (W) in step S400 f,final ) j The calculation method is:

[0081] .

[0082] The control disturbance factors injected into this example include fuel metering error, starter power decline, high-pressure compressor efficiency decline, high-pressure turbine efficiency decline, compressor rear pressure sensor error and normal range and abnormal range of starting load increase.

[0083] In one embodiment, a simulation is performed on a specific engine component-level model to verify the effectiveness of the proposed robust start control method. The method is compared with two conventional start control plans, namely, a fuel flow plan converted to pt31 (high-pressure compressor outlet total pressure) and an N-dot control plan, to prove that the method can prevent compressor surge during the start process better than the two conventional plans (the fuel flow plan converted to pt31 and the N-dot plan) under the influence of a single interference factor or a combination of interference factors, so as to verify the characteristics of the method disclosed in the present invention. The specific process is as follows:

[0084] Table 1

[0085]

[0086] Among them, HPC is the high pressure compressor and HPT is the high pressure turbine.

[0087] First, according to the provisions of the control disturbance factor size described in Table 1, assuming that under the standard atmospheric design conditions at sea level, a specific engine component-level model is not injected with a control disturbance factor and a single control disturbance factor is injected respectively, the conventional method of the fuel flow plan (CFCS) and N-dot plan (NDCS) converted by pt31, and the robust control method (IPCS) described in the present disclosure are respectively tested for the starting process, and the redundancy fuel control plan in the IPCS refers to three fuel flow plans converted by the fan inlet total pressure pt2, the fan outlet total pressure pt25 and pt31, The starting process test here refers to the acceleration process from the engine being static to the engine speed reaching the slow speed minus 1.5% of the maximum speed.

[0088] The minimum surge margin Minimum SM and start-up time in each start-up process of each method were statistically compared, as shown in Table 2.

[0089] Table 2 shows that in each simulation test of the IPCS method proposed in this paper, the performance of the two key parameters, starting time and minimum surge margin, is sometimes not optimal, but is within an acceptable range. The performance is more balanced, taking into account both starting time and minimum surge margin, while ensuring the safety and speed of the starting process, and therefore can better meet actual engineering needs.

[0090] Table 2

[0091]

[0092] Furthermore, the present disclosure also simulates and compares the three control methods through a more comprehensive combined control interference random simulation. The specific process is as follows:

[0093] Table 3

[0094]

[0095] According to the provisions of controlling the size of interference factors as described in Table 3, 1000 engine combined interference conditions are randomly selected, and each interference factor in the 1000 conditions is randomly selected from the distribution range in a uniform distribution. Assuming that under the standard atmospheric design conditions at sea level, 1000 combined interference conditions are injected into the engine component-level model respectively, and the starting process is repeated. The start-up time and Minimum SM in each acceleration process are statistically compared, as shown in Figure 2. Figures 5 and 6 And as shown in Table 4.

[0096] Table 4 shows that among the three methods, according to the starting time, whether it is the average value, the worst value or the variance, there is CFCS>IPCS>NDCS, and IPCS and NDCS are close, far less than CFCS, which means that the starting time of NDCS is the best, followed by IPCS, and the starting time of CFCS is the worst; and according to the minimum surge margin, from the perspective of the average value and the worst value, there is CFCS>IPCS>NDCS, and IPCS and CFCS are close, far greater than NDCS, but from the perspective of variance, IPCS is far less than CFCS and NDCS, which means that the minimum surge margins of IPCS and CFCS are close, both are optimal, and the minimum surge margin of NDCS is the worst. Therefore, considering the starting time and the minimum surge margin, the best choice of the three methods is IPCS.

[0097] Figure 5 It shows that the average start-up time of the IPCS method is shorter and the distribution range is narrower, indicating that the acceleration performance of the IPCS method is more robust to these disturbances. The average start-up time of the CFCS method is significantly longer, and it can be seen that the start-up time of the CFCS method is greatly disturbed, with the longest start-up time being as long as 77.1s.

[0098] Figure 6 It shows that the average minimum surge margin of the IPCS method is 4.9% higher than that of the NDCS method. Under each combination of operating conditions, the minimum surge margin of the NDCS method is smaller than that of the IPCS method, and in 299 groups of tests, the acceleration line exceeded the compressor stall line during the starting process, indicating that the engine has stalled or even surged under these test conditions.

[0099] In addition, in order to further compare the robustness of the IPCS method and the NDCS method, the minimum surge margin distribution diagrams of the proposed IPCS method and the NDCS method after the starter is disengaged are shown in Figure 2. Figure 7 shown. Figure 7 It shows that the minimum surge margin of the IPCS method is higher overall, 0.9% higher than the NDCS method on average, with a maximum difference of 2.3%. In general, only the robust control method proposed in the present disclosure can ensure that the vehicle does not approach the surge boundary under the influence of multiple combined interference factors while also avoiding a significant decrease in acceleration performance. It can be seen that this method is not only simple and easy to use, but also has obvious benefits.

[0100] Table 4

[0101]

[0102] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A robust control method for an aircraft engine starting control plan, characterized in that: The steps include: S100: During the engine start process of the aircraft engine, according to the acceleration fuel flow target (W f,cmd ) j , and the accelerated fuel flow fusion output (W f,acc ) j-1 , get the fuel deviation ; And process the fuel deviation to obtain the normalized fuel deviation ; S200: Based on normalized fuel deviation The penalty coefficient is calculated with the asymmetric Gaussian distribution function , according to the high pressure shaft conversion speed at the current time j The switching coefficient is calculated with the flexible switching function , and according to and Calculate the fusion coefficient ; S300: Calculate the acceleration target value of the high-pressure shaft according to the current time j , and the actual engine high pressure shaft conversion acceleration target value obtained at the previous moment j-1 , get the converted acceleration deviation , according to the acceleration deviation , fuel deviation and fusion coefficient Calculate the weighted sum of the deviation of the converted rotor acceleration and the fuel flow deviation , output the acceleration fuel flow fusion output (W f,acc ) j ; S400: Based on the steady-state fuel flow target (W f,steady ) j , and the acceleration fuel flow fusion output at the current time j (W f,acc ) j , and obtain the final fuel flow target (W f,final ) j .

2. The method according to claim 1, characterized in that Preferably, the normalized formula of the fuel flow deviation of the redundant fuel control plan in step S100 is: 。 3. The method according to claim 1, characterized in that In step S100, the acceleration fuel flow target (W f,cmd ) j The calculation formula is: ， in, , , and Calculate the fuel control plan corresponding to different pressure sensors at the current time j.

4. The method according to claim 1, characterized in that In step S200, the penalty coefficient , switching coefficient and fusion coefficient The calculation formula is: ； ； ； in, and is an asymmetric Gaussian distribution function with different scaling factors on the positive and negative sides, both greater than 0 and No more than 0.1, ; and are the scaling and translation coefficients of the switching function, Greater than 0 and No more than 1.

5. The method according to claim 4, characterized in that In step S300, the deviation weighted sum The calculation formula is: ， in, Adjustment The scaling factor of the size, Adjustment Scaling factor for size, both greater than 0 and not more than 10.

6. The method according to any one of claims 1 to 5, characterized in that: The final fuel flow target (W) in step S400 f,final ) j The calculation formula is: 。

Images